Oni Goroshi

In a down-on-its-luck port city the world's most skillful assassin does one last job before retiring to an idyllic life of ... just kidding, obviously; within 30 minutes of his retirement some bad guys set him on the path to a decade-spanning vendetta. The story is pretty goofy. The script can't seem to decide whether or not it wants to be taken seriously and/or how overt or illusory to make its supernatural implications. Important plot points are just retconned into existence via expositional dialogue or cutaway flashbacks.

But at least there's lots of violent bloody action and the antagonists rock some decent Oni masks. It's all style and no substance but enjoyable as over-the-top fun.